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{"version":3,"file":"until.js","sources":["../../src/directives/until.ts"],"sourcesContent":["/**\n * @license\n * Copyright 2017 Google LLC\n * SPDX-License-Identifier: BSD-3-Clause\n */\n\nimport {Part, noChange} from '../lit-html.js';\nimport {isPrimitive} from '../directive-helpers.js';\nimport {directive, AsyncDirective} from '../async-directive.js';\nimport {Pauser, PseudoWeakRef} from './private-async-helpers.js';\n\nconst isPromise = (x: unknown) => {\n return !isPrimitive(x) && typeof (x as {then?: unknown}).then === 'function';\n};\n// Effectively infinity, but a SMI.\nconst _infinity = 0x3fffffff;\n\nexport class UntilDirective extends AsyncDirective {\n private __lastRenderedIndex: number = _infinity;\n private __values: unknown[] = [];\n private __weakThis = new PseudoWeakRef(this);\n private __pauser = new Pauser();\n\n render(...args: Array<unknown>): unknown {\n return args.find((x) => !isPromise(x)) ?? noChange;\n }\n\n override update(_part: Part, args: Array<unknown>) {\n const previousValues = this.__values;\n let previousLength = previousValues.length;\n this.__values = args;\n\n const weakThis = this.__weakThis;\n const pauser = this.__pauser;\n\n // If our initial render occurs while disconnected, ensure that the pauser\n // and weakThis are in the disconnected state\n if (!this.isConnected) {\n this.disconnected();\n }\n\n for (let i = 0; i < args.length; i++) {\n // If we've rendered a higher-priority value already, stop.\n if (i > this.__lastRenderedIndex) {\n break;\n }\n\n const value = args[i];\n\n // Render non-Promise values immediately\n if (!isPromise(value)) {\n this.__lastRenderedIndex = i;\n // Since a lower-priority value will never overwrite a higher-priority\n // synchronous value, we can stop processing now.\n return value;\n }\n\n // If this is a Promise we've already handled, skip it.\n if (i < previousLength && value === previousValues[i]) {\n continue;\n }\n\n // We have a Promise that we haven't seen before, so priorities may have\n // changed. Forget what we rendered before.\n this.__lastRenderedIndex = _infinity;\n previousLength = 0;\n\n // Note, the callback avoids closing over `this` so that the directive\n // can be gc'ed before the promise resolves; instead `this` is retrieved\n // from `weakThis`, which can break the hard reference in the closure when\n // the directive disconnects\n Promise.resolve(value).then(async (result: unknown) => {\n // If we're disconnected, wait until we're (maybe) reconnected\n // The while loop here handles the case that the connection state\n // thrashes, causing the pauser to resume and then get re-paused\n while (pauser.get()) {\n await pauser.get();\n }\n // If the callback gets here and there is no `this`, it means that the\n // directive has been disconnected and garbage collected and we don't\n // need to do anything else\n const _this = weakThis.deref();\n if (_this !== undefined) {\n const index = _this.__values.indexOf(value);\n // If state.values doesn't contain the value, we've re-rendered without\n // the value, so don't render it. Then, only render if the value is\n // higher-priority than what's already been rendered.\n if (index > -1 && index < _this.__lastRenderedIndex) {\n _this.__lastRenderedIndex = index;\n _this.setValue(result);\n }\n }\n });\n }\n\n return noChange;\n }\n\n override disconnected() {\n this.__weakThis.disconnect();\n this.__pauser.pause();\n }\n\n override reconnected() {\n this.__weakThis.reconnect(this);\n this.__pauser.resume();\n }\n}\n\n/**\n * Renders one of a series of values, including Promises, to a Part.\n *\n * Values are rendered in priority order, with the first argument having the\n * highest priority and the last argument having the lowest priority. If a\n * value is a Promise, low-priority values will be rendered until it resolves.\n *\n * The priority of values can be used to create placeholder content for async\n * data. For example, a Promise with pending content can be the first,\n * highest-priority, argument, and a non_promise loading indicator template can\n * be used as the second, lower-priority, argument. The loading indicator will\n * render immediately, and the primary content will render when the Promise\n * resolves.\n *\n * Example:\n *\n * ```js\n * const content = fetch('./content.txt').then(r => r.text());\n * html`${until(content, html`<span>Loading...</span>`)}`\n * ```\n */\nexport const until = directive(UntilDirective);\n\n/**\n * The type of the class that powers this directive. Necessary for naming the\n * directive's return type.\n */\n// export type {UntilDirective};\n"],"names":["isPromise","x","isPrimitive","then","_infinity","UntilDirective","AsyncDirective","constructor","this","__lastRenderedIndex","__values","__weakThis","PseudoWeakRef","__pauser","Pauser","render","args","find","noChange","update","_part","previousValues","previousLength","length","weakThis","pauser","isConnected","disconnected","i","value","Promise","resolve","async","result","get","_this","deref","undefined","index","indexOf","setValue","disconnect","pause","reconnected","reconnect","resume","until","directive"],"mappings":";;;;;GAWA,MAAMA,EAAaC,IACTC,EAAYD,IAA8C,mBAAhCA,EAAuBE,KAGrDC,EAAY,WAEZ,MAAOC,UAAuBC,EAApC,WAAAC,uBACUC,KAAmBC,MAAWL,EAC9BI,KAAQE,MAAc,GACtBF,KAAAG,KAAa,IAAIC,EAAcJ,MAC/BA,KAAAK,KAAW,IAAIC,CAsFxB,CApFC,MAAAC,IAAUC,GACR,OAAOA,EAAKC,MAAMhB,IAAOD,EAAUC,MAAOiB,CAC3C,CAEQ,MAAAC,CAAOC,EAAaJ,GAC3B,MAAMK,EAAiBb,KAAKE,MAC5B,IAAIY,EAAiBD,EAAeE,OACpCf,KAAKE,MAAWM,EAEhB,MAAMQ,EAAWhB,KAAKG,KAChBc,EAASjB,KAAKK,KAIfL,KAAKkB,aACRlB,KAAKmB,eAGP,IAAK,IAAIC,EAAI,EAAGA,EAAIZ,EAAKO,UAEnBK,EAAIpB,KAAKC,OAFkBmB,IAAK,CAMpC,MAAMC,EAAQb,EAAKY,GAGnB,IAAK5B,EAAU6B,GAIb,OAHArB,KAAKC,MAAsBmB,EAGpBC,EAILD,EAAIN,GAAkBO,IAAUR,EAAeO,KAMnDpB,KAAKC,MAAsBL,EAC3BkB,EAAiB,EAMjBQ,QAAQC,QAAQF,GAAO1B,MAAK6B,MAAOC,IAIjC,KAAOR,EAAOS,aACNT,EAAOS,MAKf,MAAMC,EAAQX,EAASY,QACvB,QAAcC,IAAVF,EAAqB,CACvB,MAAMG,EAAQH,EAAMzB,MAAS6B,QAAQV,GAIjCS,GAAS,GAAKA,EAAQH,EAAM1B,QAC9B0B,EAAM1B,MAAsB6B,EAC5BH,EAAMK,SAASP,GAElB,KAEJ,CAED,OAAOf,CACR,CAEQ,YAAAS,GACPnB,KAAKG,KAAW8B,aAChBjC,KAAKK,KAAS6B,OACf,CAEQ,WAAAC,GACPnC,KAAKG,KAAWiC,UAAUpC,MAC1BA,KAAKK,KAASgC,QACf,QAwBUC,EAAQC,EAAU1C"} |